Abstract:

Microplastics (MPs) are ubiquitous in marine fish tissues. The accumulation of MPs and their associated pollutants in fish can reflect the distribution characteristics, pollutant sources, and ecological risk effects of MPs in marine environments. This study aimed to investigate the pollution characteristics and risk effects of MPs in fish from the Beibu Gulf aquatic environment. A total of 144 marine fish specimens from six regions were analyzed for MPs. The extraction of MPs was performed using a 10% potassium hydroxide digestion and vacuum filtration method, and their chemical composition was determined through laser Raman spectroscopy and in situ infrared spectroscopy. The contamination level of MPs in the study area was assessed using the risk index (H) and the pollution load index (P_LI) methods. The results showed that the mean abundance of gastrointestinal tract (GIT) MPs was more significant than that of the gill tissue. MPs were extracted from 46% of the fish samples, with a total of 70 MPs detected. The average ingestion of MPs per fish was 0.490, with a GIT detection rate of 36% and an average abundance of 0.417 items∙ind⁻¹, a gill detection rate of 13% and an average abundance of 0.069 items∙ind⁻¹. The detected MPs were mainly composed of red polycarbonate and polypropylene fibers ranging from 50 to 500 μm. Pearson tests showed no correlation between abundance，size and shape with habitat or diet (abundance: t=0.157, P=0.244; t=0.083, P=0.537 size: t=0.171, P=0.204; t= −0.04, P=0.767 shape: t=0.075, P=0.581; t= −0.053, P=0.696). The abundance of GIT MPs showed a strong negative correlation with fish length (r²=0.946, a= −0.013). The abundance of GIT MPs showed a weak correlation with fish weight (r²=0.365, a= −0.604). There was no correlation between the abundance of gill MPs and the fish length or weight (length: r²=0.040, a= −0.002; weight: r²=0.073, a= −0.270). The overall risk category of fish MPs in the Beibu Gulf study area was classified as level II, indicating a mild pollution level. The risk category of the Bai Majing area (S5) was classified as level Ш, indicating a higher degree of microplastic pollution in this area, with a greater variety of harmful plastic polymers. Although the gastrointestinal tract and gills of fish are removed during cooking, some smaller fish and shellfish can be consumed directly, so the health risks of MPs to humans cannot be excluded.

Key words: microplastics, distribution characteristics, risk assessment, correlation analysis, marine fish, Beibu Gulf

摘要：

微塑料（microplastics，MPs）在海洋鱼类组织中普遍存在，鱼体内的MPs及其相关污染物的积累可以反映其海洋环境中MPs的分布特征、污染物来源及其生态风险效应。为了解北部湾海洋鱼体内MPs的污染特征及其风险效应，对北部湾6个区域共144尾海洋鱼类进行MPs取样分析。通过10%氢氧化钾消解和真空抽滤方法提取鱼体内MPs，结合激光拉曼光谱和原位红外光谱仪分析MPs化学成分，利用风险指数（risk index，H）和污染负荷指数（pollution load index，P_LI）方法评估研究区域MPs污染水平。结果表明，胃肠道（gastrointestinal tract，GIT）MPs的平均丰度大于鳃的平均丰度，有46%的鱼样提取出MPs，共检测出70个MPs，平均每条鱼摄入0.490个MPs，其中GIT检出率为36%，平均丰度为0.417 items∙ind⁻¹；鳃检出率为13%，平均丰度为0.069 items∙ind⁻¹，检测到MPs以50－500 μm的红色聚碳酸酯和聚丙烯纤维为主；丰度、尺寸和形状与栖息地、食性无相关性，而胃肠道MPs丰度与鱼类全长相关性较强，呈负相关；胃肠道MPs丰度与鱼类体质量相关性弱；鳃中MPs丰度与鱼类全长和体质量无相关性；研究区域内的鱼类MPs整体风险类别为Ⅱ类，属于轻度污染，其中白马井（S5）风险类别为Ш类，说明白马井区域微塑料污染程度更严重，表现为该区域有更多种类的有害塑料聚合物。鱼类胃肠道和鳃会在烹饪过程中去除，但一些体型较小的鱼类和软体生物可直接食用，故不能排除MPs对人类的健康风险。

关键词: 微塑料, 分布特征, 风险评估, 相关性分析, 海洋鱼类, 北部湾